Method of forming photographic images



United States Patent METHOD OF FORMING PHOTOGRAPHIC MAGES Jelis de Jonge, Hendrik Jonker, Klaas Jannes Kenning, and Cornelis Johannes Dippel, Eindhoven, Netherlands, assignors, by mesne assignments, to North American Philips Company, Inc., New York, N. a corporation of Delaware No Drawing. Application September 18, 1956 Serial No. 610,677

3 Claims. (CI. 96-49) Our invention relates to methods of forming photographic contrasts with the aid of light.

This application is a continuation-in-part of application Serial No. 248,102, filed September 24, 1951, and now US. Patent No. 2,764,484. In that application we have disclosed that certain compositions, namely, metal complexes, upon exposure to light are capable of increasing the concentration of metallic mercury in the equilibrium by reacting with the mercuric ions and thus withdrawing them from the equilibrium.

In that application we have also disclosed but not claimed, other compounds which serve thesame purpose. One class of such compounds are the stable aromatic diazo cyanides corresponding to the 'formula R-N CN wherein R is an aromatic group. Examples of suitable compounds of this class are para-methoxy benzenediazocyanide, benzenediazocyanide, ortho-chloro benzenediazocyanide, para-chlorobenzenediazocyanide, para-chloroortholuene diazocyanide and para-toluene diazocyanide. These diazocyanides may be prepared by the method described in K. H. Saunders, The Aromatic Diazo-Compounds and Their Technical Application, 2nd edition, London, 1949, page 142, or by the method described by Le Fevre and Vine, Journal Chemical Society (1938), page 436.

For the manufacture of photographic images according to the invention, a lyophile layer, for example, paper, regenerated cellulose or textile may be soaked in a solution of a light-sensitive compound. Subsequent to the exposure the layer is introduced into a solution containing mercurous ions, for example 0.01 n mercurous nitrate and then into a physical developer. However, as'an alternative, the mercurous nitrate may be already added to the sensitizing liquid.

The invention will now be more fully explained by the following example:

Filter-paper is soaked in a hot ethanolic solution of one of the aforesaid diazocyanides, eg in a hot 0.1 11 solution of para-methoxy benzenediazocyanide in ethanol, said solution besides containing of glycerol and also lactic acid in a concentration of 0.05 n. After drying a strip of the light sensitive paper thus obtained is exposed for some minutes, behind a negative, to the radiation of described, for example, in US. application Ser. No.

227,564, filed May 22, 1951 now US. Patent No. 2,750,- 292, a dye image may be produced in the area of and instead of the precious metal image. Then the precious metal image may, if necessary, be eliminated by means of one of the known attenuators, so that only a dye image is left.

While we have described our invention in connection .with specific embodiments and applications, other modifications thereof will be readily apparetn to those skilled in this art without departing from the spirit and scope of the invention as defined in the appended claims.

What We claim is:

1. A method of producing photographic contrasts comprising the steps, selectively exposing a light sensitive layer containing at least one stable aromatic diazo cyanide corresponding to the formula RN --CN wherein R is an aromatic group, and then applying to said exposed layer an aqueous solution of a Water-soluble mercurous salt to form a latent mercury contrast, and physically developing the mercury contrast by applying to the mercury contrast an aqueous solution of a salt of a noble metal reducible to metal and'a reducing agent for said metal so as to deposit said noble metal on said mercury contrast.

2. A method of producing photographic contrasts comprising the steps, selectively exposing a light sensitive layer containing p-methoxy benzene diazo cyanide, and then applying to said exposed layer an aqueous solution of a water-soluble mercurous salt to form a latent mercury contrast, and physically developing the mercury contrast by applying to the mercury contrast an aqueous solution of a salt of a noble metal reducible to metal and a reducing agent for said metal so as to deposit said noble metal on said mercury contrast.

3. The method of claim '1 in which an organic dye colour photographic contrast is also formed and thereducing agent for said metal is an organic reducing agent the oxidation product of which yields an insoluble organic dyecontrast simultaneously in place with a metal contrast.

References Cited in the file of this patent UNITED STATES PATENTS Alink et a1. Ian. 12, 1937 Dippel et a1. Dec. 12, 1939 OTHER REFERENCES UNITED STATES PATENT @FFIQE February 2 1960 Jelis de Jopge e1; alv

rtified that error appears in the ab tion and that the sen.

ove numbered patuld read as It is Hereby ce d Letters Patent sho en't requiring; correc corrected belowo Column 2 line E5 after "citric" insert acid Signed and sealed this 23rd day of May i961o (SEAL) Attest: ERNEST SWEDER DAVID L. LADD Commissioner of Patents Attesting @fficer 

1. A METHOD OF PRODUCING PHOTOGRAPHIC CONTRASTS COMPRISING THE STEPS, SELECTIVELY EXPOSING A LIGHT SENSTIVE LAYER CONTAINING AT LEAST ONE STABLE AROMATIC DIAZO CYANIDE CORRESPONDING TO THE FORMULA R-N2-CN WHEREIN R IS AN AROMATIC GROUP, AND THEN APPLYING TO SAID EXPOSED LAYER AN AQUEOUS SOLUTION OF A WATER-SOLUBLE MERCUROUS SALT TO FORM A LATENT MERCURY CONTRAST, AND PHYSICALLY DEVELOPING THE MERCURY CONTRAST BY APPLYING TO THE MERCURY CONTRAST AN AQUEOUS SOLUTION OF A SALT OF A NOBLE METAL REDUCIBLE TO METAL AND A REDUCING AGENT FOR SAID METAL SO AS TO DEPOSIT SAID NOBLE METAL ON SAID MERCURY CONTRAST. 